// = 赋值重载
// 注意 = 重载时，可能会调用类本身的拷贝构造函数。如果左值是没有创建的对象时，
// 会调用类的拷贝构造函数
#include <iostream>
#include <cstring>
#include <cstdlib>

using namespace std;

class A
{
private:
    int x;

public:
    A(int x) : x(x)
    {
        cout << "A(int x)" << endl;
    }
    A(const A &obj)
    {
        cout << "A(A &obj)" << endl;
        this->x = obj.x;
    }
    A &operator=(const A &other)
    {
        cout << "A &operator=(A&other)" << endl;
        this->x = other.x;
        return *this;
    }

public:
    void show()
    {
        cout << "x = " << x << endl;
    }
};

int main()
{
    A a1(100), a2(200);
    A a4 = 300; // A(300)
    a4 = 400;   // operator=()

    A a3 = a1; // A(a1)
    a3.show();

    a3 = a2; // operator=() 调用赋值重载函数
    a3.show();

    a3 = a4;
    a3.show();

    return 0;
}